CDKN1B and polycythemia: Simvastatin treatment potently inhibits vascular remodeling by attenuates chronic hypoxic pulmonary hypertension and polycythemia in rats [33], and reverses pulmonary arterial neointimal formation and PAH after toxic injury by down-regulating the inflammatory genes fos, jun, and tumor necrosis factor-α and up-regulating the cell cycle inhibitor p27Kip1, endothelial nitric oxide synthase, and bone morphogenetic protein receptor type 1a [31].